#include<stdio.h>

int cal(int*arry,int x)
{
    int count=0,y=0;
    for(y=0;y<x-1;y++)
    {
        count+=*arry;
        arry++;
    }
     return count;
}
int main() {
    int a, b=0,n;
    int number[]={0};
    int *num=number;

    scanf("%d",&n);
    do{
        scanf("%d",&number[b]);
        b++;
    }while(b<=n-1);
    int cal(int*num,int n);
    return 0;
}